First, based on the theory of Fresnel diffraction, the diffraction patterns are analyzed when the point source at the frontfocus or it's nearby of the lens.
首先，利用菲涅耳衍射理论，分析了无衍射成像系统中点光源在透镜焦点及焦点前后所产生的无衍射光斑形式。
2
When a lion tamer holds a chair in front of the lion's face, the lion tries to focus on all four legs of the chair at the same time.
当驯兽师举起一把椅子在狮子面前时，它会试着把注意力同时放在椅子的四条腿上。
3
Learn to focus on what's in front of you, and find peace in whatever you do.